Effects In Thar-Nagar Parker Region Of Sindh, Se Pakistan

Geological Bulletin Univ. Peshawar Vol. 35, pp. 9-26,2002 11Fig. 1. Geographical sketch map of SE Sindh (Pakistan) and Gujarat province of India, showing location of thestudied area of Thar-Nagar Parkar, separated from Kuchchh Mainland by Rann of Kuchchh. Epicentre ofthe Bhuj Earthquake January 2001 is shown for reference.

Geological Bulletin Univ. Peshawar Vol. 35, pp. 9-26,2002 13Fig. 2. Cambay rift province in SE Sindh and Kuchchh region (Modified after Biswas, 1982; Ahmed et al., 1994).Note that a limb of the Cambay Rift stretches across SE Sindh in a NW-SE direction including several horstgrabenstructures overlain by Cretaceous and younger sediments. Kuchchh basin is a WSW-ENE rift basinat right angle to Cambay Rift. Inversion tectonics of these normal faults in response to ongoing N-Scompression is source of seismicity in the region.incompact clay, slit and sand, 3) 0-185 meters ofstratified rocks ranging in age from Jurassic toEocene including up to 25 meter thick seams oflignite in the upper part, 4) granitic basement atdepths of 112-279 meters. In an area of - 500 km2at the southeastern extremity of the desert, in thevicinity of the Nagar Parkar Town, this basementrockis exposed as a suite of Late Proterozoic A-type

Geological Bulletin Univ. Peshawar Vol. 35, pp. 9-26,200249 70IIGreat Rann of Kuchchh-0 10 20Kmplunge direction;: Synclinal 0x1s withplunge dlredionFig. 3. Regional tectonic map of Kuchchh region showing major geomorphic zones separated by regional faults(Malik et al., 2000).granites in the form of sporadic hills, intruded in aProterozoic basement comprising amphibolites. Thispart of the Thar Desert represents a major uplift inthe region, resulting in the absence of rocks youngerthan Late Proterozoic, probably due to erosionfollowing the uplift. A buried fault with uplift of -150meters of this area relative to NW coal-bearing areamarks the boundary of this uplifted area to the NW(Kazmi, 1984). Being a part of the western Indianshield, the Nagar Parkar granites and their hostbasement amphibolites belong to the post-Dehlitectonic/anaorogenic magmatic event dated around850-750 Ma in the Aravali Craton (Roy, 1988). TheNagar Parkar Igneous Complex (Jan et al., 1997)res ernbles closely with gr~tes fr-Siwana andJalore in western Rajhstan, which yield Rb-Sr ages of698 and 728 Ma.- - - - - - -Depth to the basement relative to the surfaceincreases westward in the Thar desert. Whereas inthe vicinity of Nagar Parkar village the basement isexposed at the surface, it gradually deepens to depthsof 1500 m short of Mithi (Fig. 4). The depth tobasement increases further west towards the currentlocation of the Indus River, where it approaches toa depth of 3.5 km. A cross section across the Indusplatform from the border area in the Thar desert tothe Indus river (Fig. 5) depicts a west-facing pre-Paleocene halfgraben structure, with basement highunderlying the Thar desert. A sedimentary wedgecomprising sediments from Permian to Recent fillsthis graben structure, with base of the PalaeoceneUpper Guru Formation defining a post-rift angularunconformity. Ofparticular interest to this study andliquefaction hazards in lower Indus Basin is the thick

Geological Bulletin Univ. Peshawar Vol. 35, pp. 9-26, 2002 22Photo 9-10. Closeview of individual sand blow. This wasthe typical liquefaction feature in responseto the Bhuj earthquake in much of the Rannof Kuchchh area and the southern Thardesert.Photo 13,14,15. Close ups of ~ndividual fractures. Notein one case the fractures traverse across theun-metalled road.Photo 11. Margin of an interdunal lake adjacent to astable dune. Note that the entire margin islined up with a series of sand blows, whilethe dune suffered lateral spreading fracturesparallel to the length of the dune.Photo 12. Margin of a stable sand dune with fractures inresponse to lateral spreading liquefaction.- ----- ---- ----/-APhoto 16, 17. Stable dunes showing a series offZcturSrelated with lateral spreading liquefaction.Whereas in most cases such fractures werefound parallel to the axis of the dune, but inrare case they traversed across the dunes.8 -

Geological Bulletin Univ. Peshawar Vol. 35, pp. 9-26, 2002 23Photo 18. A view of a village (Tobo) southwest of Diplolocated at the crest of a stable dune. Some20-30 mud and cane houses completely orpartially collapsed in response to fracturesrelated with the lateral spreading.DISCUSSIONSThe Bhuj earthquake 2001 was one of the majorearthquakes to occur in the vicinity of Pakistan in therecent past. The earthquake was felt all over theSindh province, but damage occurred within a radiusof 300 km from the epicenter (i.e., region fallingwithin 150 km from the border at the Rann ofKuchchh). Widespread liquefaction reflected in sandblows and filling of inter-dunal depressions fromupwelling groundwater together with lateral spreadingin the stable dunes occurred in a belt of about 20krn width all along the southern margin of the Thardesert facing the Rann of Kuchchh from Nagar Parkarin the east to ~ li~ander in the west. Mud and canehuts in several villages situated at dune crestspartially collapsed with minor injuries to a fewpeople. Since this area has only scarce populationand masonry buildings are virtually non-extent,damage was far less than expected. The Nagar Parkartown and surrounding villages, where only a thinveneer of sand and soil covers the solid bedrock,liquefaction effect was almost negligible. All thedamage to buildings in this area occurred to groundshaking. Even in this area, mud houses with lightroofs made up ofcanes faired better than the masonrybuildings. The old masonry building (stone in mortar)in the Nagar Parkar town did develop cracks butstill faired better than the masonry buildings withconcrete roofs built within last few years mostly bygovernmental departments (e.g., schools, disy ensaries,rest houses), which suffered partial or completecollapse. This was due to poor quality of materialbeing used in governmental buildings. A third areawhere masonry buildings suffered damage to theextent ofpartial collapse included the northern TharDesert. Depth to bedrock in this area is as great asin the southern Thar Desert. This area has 1) lowwater table, 2) active dunes with thick cover of freshunconsolidated sand. This area either did not sufferany liquefaction due to low water table or if theliquefaction did occur fresh sand instantly coveredthe resulting fractures. The damage to masonrybuildings in this area was probably due to groundshaking,Many news papers in their columns rightlytermed the Bhuj Earthquake 2001, as a wake-up callfor Sindh province especially the highly populatedand congested cities of Karachi and Kyderabad.Already people have speculated that how did SESindh province escaped major damage even in responsethe Bhuj earthquake, when cities after citieswere completely flattened in the Gujarat province ofIndia. Hussain et al. (2002) speculated that probablythe thick cover of soil on deeper-seated bedrock inThar and lower Indus basin served as a cushionhampering the ground shaking. This is a completemisapprehension of the processes involved in propagationand amplification ofthe seismic waves. One ofthe basic concepts of the earthquake science is thatpoorly consolidated material such as the recentsediments covering the lower Indus basin and thethick sand dunes in the Thar Desert would amplifythe ground shaking rather than hampering it (References).The primary reasons that SE Sindh y rovinceescaped substantial damage was due to its distancefrom the epicenter (> 150 krn at any point). Secondlythe region that was most susceptible to damage i.e.,the southern Thar desert, is most scarcely populated.Thirdly, most of the houses in the Thar deserthave low mud walls (or rarely stone in mud mortar)with very light roofs made up wooden sticks or canes.The nearest villages/towns with masonry buildings

Geological Bulletin Univ. Peshawar Vol. 35, pp. 9-26, 2002 24included Diplo (185 km Distance from the epicenter),Nagar Parkar (1 15 Km). These villages sufferedconsiderable damage to buildings and even a partialcollapse but time of the earthquake (9 am) was suchthat most people were out of their houses, thathelped to have a minimum damage to life.As far as the seismic hazard potential of thelower Indus basin and the Thar desert is concerned,a disaster at the scale of Bhuj earthquake is expectedif a major earthquake with magnitude > 6 strikes theregion with an epicenter located closer than that ofthe Bhuj earthquake. In terms oftectonics, the datafrom theBhuj earthquake reveals that normal faultsrelated with Cretaceous Cambay rift are subject toinversion tectonics. No surface scarp of the fault thatcaused the Bhuj earthquake is confirmed so far,although up to 2 krn long zones of intense lateralspreading at N 23" 20' 30.4" E 70 11' 40.1" to N 2320' 30" E 70 11' 53.9" could be manifestation of asubsurface scarp ( Miranda, 2001). Aftershockseisrnity suggests that the fault plane responsible forthe Bhuj earthquake orientedENE-WSW with a dipof 45-50'. Existing fault plane solutions vary, butthere is a general consensus that the Bhuj earthquake,in analogy with 1956 Anjar earthquake and18 19 earthquake of Allaband indicate reverse faulting(Rastogi et al., 2001). Since the Bhuj earthquakepartially reactivated the Kuchchh Mainland Fault,that was a Cretaceous normal fault associated withKuchchh graben, it appears that current N-S compressionbetween the Indian plate andthe Himalayasis causing inversion tectonics. As shown in Figure(Z), SE Sindh province is underlain by a whole arrayof normal faults with intervening horsts and grabenstructures. This region intervenes between Kuchchhseismic zone in the south and Chaman seismic zonein the NW, which warrants special attention withregards to potential. future seismic hazards faced bythe Sindh province.In case of a local reactivation of any of theCretaceous normal faults underlyingthe lower Indusbasin and the Thar desert, the thick cover ofrecentunconsolidated sediments in the region is mostsusceptible to liquefaction hazards. Additionally,these sediments are capable of amplifying the seismicwaves far greater than the bedrocks. Figure (5) showsthat recent sediments in the lower Indus basin attainthickness of up to 30 km. With a high water table,the entire lower Indus basin is susceptible to intenseliquefaction. Sinking and complete collapse of thehistorical town of Samaji in 1668 (located to thesouth of Hyderabad) can be taken an example ofthedevastation liquefaction in lower Indus basin cancause.Unfortunately, Pakistan is completely unpreparedfor seismic hazards. Firstly, the population isgrowing at alarming rates, which coupled with migrationto cities is causing fast but uncontrolled growthof urban centers. Building codes are either inappropriateor non-existing. Implementation of the buildingcodes is even worse. Public awareness of earthquakehazards is extremely poor and there is hardlyany disaster management programme at public orgovernmental level. Above all there is a drastic lackof lack of scientific data about the potential seismichazards in the country. There is an urgent need forinstallation of a network of seismic stations all overthe country so that reliable seismicity data arecollected locally. Likewise a network of oscillometresas well as a network of Global Position Systems needto be established so that not only instrumentalintensities are regularly recorded but reliable data ofneotectonic activity is available to the scientists forassessing true seismic hazards faced by differentparts of the country. These studies are important inorder to assess the potential seismic risk to over 30million population in Sindh. Additionally large infrastructuressuch as the proposed Thermal PowerPlant at Islamkot using Thar coal deposits to generateelectricity need proper assessment of seismichazards before their structural designing.Acknowledgements:This work was partially fundedby a grant from National Science Foundation to RogerBilham. Transport and other logistic support for thefieldwork was provide by the Geological Survey ofPakistan, for which the authors are indebted to Mr.

Geological Bulletin Univ. Peshawar Vol. 35, pp. 9-26,2002 25Hazasn Gohar, Abbas Ali Shah and MimaTalib. Manypeople from the region assisted in fieldworkand datacollection, especially Mr. Nawaz Ali Khosa fromNagar Parkar whose able guidance was of immensehelp in locating the surface damage and collection ofadditional data including the discovery of three GTSSurvey Points (1856).REFERENCESAhmed, R. Ali, M., and Ahmad, J. 1994. Review ofPetroleum occurrences and prospects of Pakistanwith reference to adjoining basins ofIndia, Afghanistan and Iran. Pakistan Journal ofHydrocarbon Research, 6, 7- 18.Bilham, R, 1999. Slip parameters for the Rann ofKachchh, India, 16 June 1819 earthquakequantified from contemporary accounts, inStewart, I. S. & Vita-Finzi, C. (Eds) CoastalTectonics. Geological Society London, 146,295-3 18Biswas, S. K. 1982. Rift basins in western margin ofIndia and their hydrocarbon prospects with specialreference to Kutch basin. A. A. P. G. Bull. 66,1497-1513.Biswas, S. K. 1987. Hydrocarbon exploration inwestern offshore basins of India, in RecentGeoscientific studies in the Arabian Sea off India,Geol. Survey of India, Spec. Pub. 24, 185-194,1987.Chandra, U. 1975. Fault plane solution and tectonicimplications of the Patan, Pakistan earthquakeof December 28, 1974. Tectonophysics 28,T19-T24.Chandra, U., 1997. Earthquakes of Peninsula India - aseismotectonic study. Bull. Seisrnol. Soc. Am., 67,- 438LUl3------ ---------Chung, W.-Y. and H. Gao. 1995. Source mechanismof the Anjar, India, earthquake of 21 July,1956 and its seismotectonic implications forthe Kutch rift basin, Tectonophysics, 242,281 -292.Fassett, J. E,, 1994. Geology and Coal Resources of theThar Coal Field, Sindh Province, Pakistan. USGSOpen-File report 94-0167.Fassett, J.A., and Durrani, N.A. 1994, Geology and coalresources of the Thar coal field, Sindh Province,Pakistan: U.S. Geological Survey Open-File Report94-167, 74 p.Jackson, J. and Yielding, G. Y. 1983. The seismicity ofKohistan, Pakistan: source studies of the Harman(1972.9.3), Dare1 (1981.9.12) and Patan (1974.12.28) earthquakes. Tectonophysics 91, 15-28.Jan, M. Q., Laghari, A. &Khan, M. A. 1997. Petrographyof the Nagar Parkar Igneous Complex Tharparkar,Southeast Sindh. Geol. Bull. Univ. Peshawar 30,227-250.Johnston, A. C. and Kanter, L. R, 1992, Stable ContinentalEarthquakes, Sci. Am. 262, 68-75.Kadri, I. 1994. Petroleum Geology of Pakistan. PakistanPetroleum Limited, 269p.Kazrni, A. H. and Jan M. Q. 1997. Geology and Tectonicsof Pakistan. Graphic Publishers, Karachi, 554p,Kazmi, H. A. 1984. Geology of the lndus delta. In:Marine Geology and Oceanography of ArabianSea and Coastal Pakistan (Haq, B. U. and Milliman,J. D. Eds.). Van Nostrand Reinhold Company.New York. 71-84.Khattari, 1992 Khattri, K. N. 1994, A hypothesis for theorigin of Peninsular seismicity, Current Science,67, 8, 590-597.Malik, J. N., Sohoni, P. S., Merh, S.S., and Karanth, R.V. 2000. Palaeoseisrnology and neotectonism ofKachchh, Western India. .In: Active Fault Researchfor the New Millennium, Proceedings ofthe Hokudan International Symposium and Schoolon Active Faulting (Okumura, K., Goto, H., andTakada, K., eds). 251-259.Miranda, E, 2001. http:llcires.colorado.edu/-bilham/BhujOyoThrust.html.---------------Oldham R.D., 1926, The Cutch (Kachh) earthquake of16th June 1819 with a revision of the greatearthquake of 12th June 1897. Mem. Geol. Surv.of India, 46, 71 - 146.Quittmeyer, R. C. and K. H. Jacob, 1979, Historical andmodern seismicity ofPakistan, Afghanistan, northernIndia and southern Iran, Bull. Seisrnol. Soc.Am, 69., 773-823.

Geological Bulletin Univ. Peshawar Vol. 35, pp. 9-26,2002 26Ramanathan, K and Mukerji, S. 1938. A seismologicalstudy of the BaIuchistan, Quetta earthquake ofMay 31,1935. Kec. Geological Survey of India, 73,483-513.Rastogi, B. K., Gupta, H. K,, Manadal, P., Satyanarayana,H. V. S., Kousalya, M., Raghavan, R., Jain, R.,Sarrna, A. N. S., Kurnar, N., and Satyamurty, C.2001. The deadliest stable continental regionearthquake occurred near Bhuj on 26 January2001. journal of Sedimentology, 5, 609-615.Rehman, M. U., Zaigharn, N. A., Nizamani, M. A.,Ahmad, M., and Huda, Q. U. 1993. Coal explora-tion in Tharparkar, Sindh, Pakistan: Geol. Surv.Pak. Record No. 95, 35p.Roy, A. B. 1988. Stratigraphic and tectonic frameworkof the Aravalli Mountain range. In: Precambrianof the Aravalli Mountains, Rajasthan, India (Roy,A. B.Ed.). Geol. Soc. India, Mem 9, 3-21.Yeats, R. S., Sieh, K., and Allen, C. R. 1997. The geologyof Earthquakes. Oxford University Press.Zaigham, N. A. 2000. Strategic sustainable developmentof groundwater in Thar Desert of Pakistan.http:llwww.cornsats.org.pk/latest/nayyer-alam-zaigh am.pdf